Armature going crazy
Backup you latest defective file and work with a copy.

The armature modifier can be deleted and then a second bind to armature can be performed.

Deleting an armature modifier may sound error prone.  Yet Blender features can be deleted and recreated.

If you saved the binding position for example in Frame 1 then you can simply bind a second time.

It is unfortunate that you had this location of mesh accident.  There are many ways this can happen. One is moving the keyframed mesh and NOT setting a location keyframe. Keyframe mesh position in frame 1. 

You may choose to move your mesh to the origin.  Place the armature and bind to armature correctly.  Frame 1.

You may consider in the future that you may rebind at any time in Frame 1.